The present invention relates generally to a fluid refrigeration and delivery system, and more particularly, to a fluid refrigeration and delivery system used in connection with surgical or other medical procedures in which chilled fluid is periodically administered to a patient.
Heart surgery often requires that the surgeon terminate the functioning of the heart without damaging the heart muscle. This is accomplished by injecting a chilled cardioplegic fluid through a catheter into the aortic root of the heart. The chilled cardioplegic fluid lowers the temperature of the heart thereby causing it to cease pumping.
The conventional mode of chilling and administering the cardioplegic fluid is manifestly inadequate. The cardioplegic fluid, contained in the conventional IV plastic bag, is chilled in a refrigerator prior to the operation. Shortly prior to the operation the IV bag containing the chilled cardioplegic fluid is removed from the refrigerator, placed in a bucket of ice, and brought to the operating room. When it is time to administer the cardioplegic fluid, the IV bag is hung on an IV pole. A plastic tube is connected to the discharge outlet of the IV bag and to a catheter. The tubing is clamped to restrain the flow of cardioplegic fluid until the surgeon is ready to administer it.
The surgeon, prior to administering the cardioplegic fluid to the heart, must initially purge the tubing of the fluid because its temperature will rise quickly to an unacceptable level due to the warm tubing. After purging a sufficient quantity of cardioplegic fluid through the tubing, chilled fluid is available for administration to the patient. The surgical procedure begins as soon as a sufficient quantity of chilled cardioplegic fluid has been injected into the heart to cause it to cease pumping. The temperature of the heart gradually rises and prior to attaining a temperature level that would cause it to start functioning, the surgeon must reinsert the catheter and supply another quantity of chilled cardioplegic fluid to the heart. However, during the time span after the initial administration of the cardioplegic fluid, the fluid in the tubing begins to warm up as does the fluid in the IV bag which is subjected to room temperature, although its temperature increases at a slower rate. The surgeon must therefore again purge the warmed fluid from the tubing so that the cooler fluid in the bag is available for administration to the patient.
There are numerous problems associated with such a crude refrigeration and delivery system. First, there is no temperature control for the cardioplegic fluid. Since the IV bag on an IV pole at room temperature, the fluid's temperature gradually rises, and since the IV bag is stored in a bucket of ice, its initial temperature can be no lower than about 0.degree. C. Consequently, the effectiveness of the cardioplegic fluid decreases rapidly as the surgery progresses. Often even though the fluid is only partially used, a fresh IV bag from the ice bucket must be used because the fluid in the first bag becomes too warm. The employment of ice for cooling is unsanitary and inconvenient. There is also a problem of maintaining ideal sterile conditions in the vicinity of the operating table. Also, moisture condenses on the IV bag causing difficulty in visually monitoring the amount of fluid used. Finally, the purging procedure to rid the tubing of warmed cardioplegic fluid wastes time. The heart may enter a hypoxic condition creating a situation in which damage to the heart muscle may result.
It is the object of the present invention, therefore, to provide a fluid refrigeration and delivery system particularly adapted for use in the health care field.
It is another object of the present invention to provide a refrigeration system having novel evaporator members for supporting IV bags to promote conduction of heat from a solution in the bag to the evaporator sleeve.